TEPZZ 9 Z79A_T EP A1 (19) (11) EP A1 (12) EUROPEAN PATENT APPLICATION

Transcription

1 (19) TEPZZ 9 Z79A_T (11) EP A1 (12) EUROPEAN PATENT APPLICATION (43) Date of publication: Bulletin 2015/39 (21) Application number: (51) Int Cl.: H01H 31/12 ( ) H01H 69/02 ( ) H01H 85/042 ( ) (22) Date of filing: (84) Designated Contracting States: AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR Designated Extension States: BA ME Designated Validation States: MA (30) Priority: US P US (72) Inventors: Siebens, Larry N. Asbury, NJ New Jersey (US) Gardner, Daniel L. Stewartsville, NJ (US) Haynes, Gary Sorrento, FL Florida (US) (74) Representative: Carpmaels & Ransford LLP One Southampton Row London WC1B 5HA (GB) (71) Applicant: Thomas & Betts International, LLC Wilmington, DE (US) (54) Fuse insulating support bracket with pre-molded shed (57) A support bracket for a fuse cutout may include an insulating rod with a first threaded standoff at a top end of the insulating rod and a second threaded standoff at a bottom end of the insulating rod. One or more shed sleeves may be secured over an outside surface of the insulating rod between the first threaded standoff and the second threaded standoff. The interior surface of the one or more shed sleeves forms a dielectric interface between the outside surface of the insulating rod and the interior surface of the shed sleeve. A mounting bracket may be secured to a portion of the support bracket between the first threaded standoff and the second threaded standoff. The one or more shed sleeves may be premolded prior to installation over the insulating rod. EP A1 Printed by Jouve, PARIS (FR)

2 1 EP A1 2 Description CROSS-REFERENCE TO RELATED APPLICATION [0001] This application claims priority under 35 U.S.C. 119, based on U.S. Provisional Patent Application No. 61/968,020 filed March 20, 2014, the disclosure of which is hereby incorporated by reference herein. BACKGROUND OF THE INVENTION [0002] The present invention relates to a fuse cutout that can be used with power distribution systems to protect against electrical overload. Outdoor cutouts, such as a high voltage dropout fuse, may provide overcurrent protection for equipment that can be damaged by system overload or fault conditions. Such outdoor cutouts may be used to clear fault or overload currents on a section of an overhead distribution line or a damaged piece of equipment. [0003] An outdoor cutout may include a fuse tube (including a fuse element) and a mounting insulator that electrically isolates the conductive portions of the cutout from the support to which the cutout is fastened. The mounting insulator typically includes an outer shield. The outer shield generally includes a number of radially extending fins for increasing creep and flashover distance on the exterior of the insulator. In conventional systems, the outer shield is formed by over-molding the insulator as a single piece. BRIEF DESCRIPTION OF THE DRAWINGS [0004] Fig. 1 is a side view illustrating a fuse cutout assembly according to an implementation described herein; Fig. 2 is a side view and a top view of the support bracket of the fuse cutout assembly of Fig. 1; Fig. 3 is an exploded side assembly view of the support bracket of Fig. 2; Fig. 4 provides a bottom view of an upper shed sleeve and a top view of a top portion of an insulating rod of Fig. 3; Fig. 5A is side perspective view of an upper shed sleeve of the support bracket of Fig. 2; Fig. 5B is side perspective view of another upper shed sleeve according to another implementation described herein; Fig. 6 is an exploded side view showing a mounting bracket with a side cross-section view of an upper shed sleeve, according to another implementation described herein; Fig. 7 is a side view of a support bracket for a fuse cutout assembly, according to another implementation described herein; and Fig. 8 is a flow diagram of an exemplary process for assembling a support bracket for a fuse cutout, according to an implementation described herein. DETAILED DESCRIPTION OF THE PREFERRED EM- BODIMENTS [0005] The following detailed description refers to the accompanying drawings. The same reference numbers in different drawings may identify the same or similar elements. [0006] Systems and/or methods described herein relate to a support bracket for a fuse cutout. In one implementation, the support bracket may include an insulating rod with a first threaded standoff at a top end of the insulating rod and a second threaded standoff at a bottom end of the insulating rod. One or more shed sleeves may be secured, via an interference fit, over an outside surface of the insulating rod between the first threaded standoff and the second threaded standoff. The interior surfaces of the one or more shed sleeves form a dielectric interface between the outside surface of the insulating rod and the interior surface of the shed sleeve. A mounting bracket may be secured to a portion of the support bracket between the first threaded standoff and the second threaded standoff. The one or more shed sleeves may be pre-molded prior to installation over the insulating rod. [0007] In another implementation, a support bracket for a fuse cutout may include an insulating rod having a top portion, a bottom portion opposite the top portion, and a middle portion between the top portion and the bottom portion. A first shed sleeve may be secured, via an interference fit, over an outside surface of the top portion, such that an interior surface of the first shed sleeve forms a dielectric interface between the outside surface of the top portion and the interior surface of the first shed sleeve. Similarly, a second shed sleeve may be secured, via another interference fit, over an outside surface of the bottom portion, such that an interior surface of the second shed sleeve forms a dielectric interface between the outside surface of the bottom portion and the interior surface of the second shed sleeve. A mounting bracket may be secured to the middle portion of the insulating rod between the first shed sleeve and the second shed sleeve. [0008] Fig. 1 provides a diagram of an exemplary device in which systems and/or methods described herein may be implemented. In one implementation, device may include a fuse cutout assembly. Device may be used, for example, on overhead power distribution systems. [0009] As used in this disclosure with reference to the apparatus (e.g., device ), the term "high voltage" refers to equipment configured to operate at a nominal system voltage above 3 kilovolts (kv). Thus, the term "high voltage" refers to equipment suitable for use in electric utility service, such as in systems operating at nominal voltages of about 3 kv to about 38 kv, commonly referred to as 2

3 3 EP A1 4 "distribution" systems, as well as equipment for use in "transmission" systems, operating at nominal voltages above about 38 kv. [00] Device may generally include a support bracket 0 that supports a fuse assembly 200. Device may provide overcurrent protection for equipment that can be damaged by system overload or fault conditions. As shown in Fig. 1, device is typically mounted with fuse assembly 200 at an angle to allow a portion of fuse assembly 200 to rotate and fall open under its own weight when a fuse blows. More particularly, when an overload condition occurs, a fuse link in fuse assembly 200 will melt causing fuse assembly 200 to drop and interrupt current through device. [0011] Fig. 2 includes a side and top views of support bracket 0, and Fig. 3 is an assembly or exploded view of support bracket 0. Referring collectively to Figs. 2 and 3, support bracket 0 may include an insulating rod 2 with a mounting bracket 4. Insulating rod 2 may include a solid insulating core 3 with a threaded standoff 8 at each end of insulating rod 2. Insulating core 3 may include, for example, a fiberglass material or another insulating material. For example, insulating core 3 may include a glass-reinforced epoxy laminate tube in accordance with National Electrical Manufacture Association (NEMA) designation G- or FR-4. [0012] Mounting bracket 4 may include an elbow section 5 and a ring 6 formed, for example, of galvanized steel. Elbow section 5 (also referred to as a flange) may include a mounting aperture and an angled frame to allow device to be mounted to a grounding element at an angle from vertical (e.g., as shown in Fig. 1). Ring 6 of mounting bracket 4 may be slid over insulating rod 2 and secured to a middle portion of insulating rod 2 using a pin 7 inserted through insulating core 3 and ring 6. [0013] Each threaded standoff 8 may include, for example, a male or female hex connector with a stud mounted thereon. The hex connector of threaded standoff 8 may be mounted to an end of insulating core 3 so as to form a shoulder 9 at the interface of insulating core 3 and threaded standoff 8. In one implementation, threaded standoff 8 may receive an end bracket 1 (which may abut against shoulder 9), secured via a washer 112 and a nut 114 onto the stud of standoff 8. To keep end bracket 1 from rotating, a hex shaped aperture may be machined into end bracket 1 to match the hex shape portion of threaded standoff 8. When end bracket 1, washer 112, and nut 114 are secured to each threaded standoff 8 at the ends of insulating rod 2, fuse assembly 200 may be mounted to each end bracket 1. [0014] Support bracket 0 may also include an upper insulator shed sleeve 120 and a lower insulator shed sleeve 130 (referred to herein collectively as "insulator shed sleeves 120/130" or generically as "insulator shed sleeve 120/130") to prevent voltage flashover or voltage tracking due to moisture and contamination. Insulator shed sleeves 120/130 may generally be formed from, for example, a dielectric silicone, a thermoplastic elastomer or rubber, which is vulcanized under heat and pressure, such as an ethylene-propylene-dienemonomer (EPDM) elastomer. According to implementations described herein, insulator shed sleeves 120/130 may be pre-molded components with an interior bore that is sized to be forced over the circumference of insulating rod 2 and maintain position via an interference fit with insulating core 3. In one implementation, the pre-molded shed sleeves 120/130 may be manufactured in an automated manner that removes the flash (e.g., unwanted material left by the molding process) without manual processing. [0015] The outer surface of insulating core 3 (e.g., along the circumference of insulating rod 2) is generally smooth and cylindrical to provide clean contact with an interior surface of each insulator shed sleeve 120/130. The interference fit (also referred to as a friction fit) ensures that an interior surface of each insulator shed sleeve 120/130 forms a dielectric interface between the outside surface insulating rod 2 and insulator shed sleeve 120/130. [0016] In some implementations, insulator shed sleeves 120/130 may each include a number of radially extending fins 122/132 for increasing a creep distance on an exterior of support bracket 0. Fins 122/132 may be desirable in above-ground or weather-exposed switch installations. Increased creep distance may be provided, for example, by changing the spacing and/or dimensions of fins 122/132 on insulator shed sleeves 120/130. [0017] In one implementation, the configuration of upper insulator shed sleeve 120 and lower insulator shed sleeve 130 may be identical to provide interchangeable components for upper insulator shed sleeve 120 and lower insulator shed sleeve 130. In another implementation, as shown in Figs. 1-3, upper insulator shed sleeve 120 and lower insulator shed sleeve 130 may be substantially similar, but fins 122 and fins 132 may have a slope 123/133 in opposite directions (e.g., so as to provide slopes in the same direction when upper insulator shed sleeve 120 and lower insulator shed sleeve 130 are installed on opposite ends of insulating rod 2). In still other implementations, upper insulator shed sleeve 120 and lower insulator shed sleeve 130 may have different axial lengths and/or different amounts of fins 122/132 (e.g., depending on the installed location of mounting bracket 4). [0018] As shown in Fig. 3, upper shed sleeve 120 and lower shed sleeve 130 may slide over the top and bottom ends of insulating rod 2, respectively. In some embodiments, upper shed sleeve 120 and lower shed sleeve 130 may be held in place on insulating rod 2 via an interference fit. That is, upper shed sleeve 120 and lower shed sleeve 130 may each have a central bore (references 124 and 134, respectively) with a circumference sized such that it may be stretched over the circumference of insulating core 3. The interference fit provides a substantially void-free dielectric interface between the 3

4 5 EP A1 6 outside surface of insulating core 3 and the interior surfaces of insulator shed sleeves 120/130 (e.g., along central bores 124/134) without using a bonding agent. In one implementation, insulator shed sleeves 120/130 may be pushed over insulating rod 2 without any additional materials (such as sealants, lubricants, or adhesives) used at the interface between the outside surface of insulating rod 2 and the interior surfaces of insulator shed sleeves 120/130. [0019] Fig. 4 provides a simplified bottom view of upper shed sleeve 120 and a simplified top view of insulating rod 2 to illustrate the interference fit of upper shed sleeve 120 and insulating rod 2. Lower shed sleeve 130 may be configured similarly to upper shed sleeve 120 to provide a similar interference fit of lower shed sleeve 130 and insulating rod 2. As shown in Fig. 4, an outside diameter 118 of insulating rod 2 is larger than the inside diameter 128 of central bore 124 of upper shed sleeve 120. The interior surface of upper shed sleeve 120, along central bore 124, is generally smooth and cylindrical. Thus, upper shed sleeve 120 can be stretched, manipulated, pushed, and/or forced over insulating rod 2 to provide an airtight/watertight fit with a consistent hoop force being applied to insulating rod 2 upon installation. The interference fit between insulating rod 2 and upper shed sleeve 120 may provide a dielectric interface between insulating rod 2 and upper shed sleeve 120. Lower shed sleeve 130 may be applied over a different portion of insulating rod 2. For example, upper shed sleeve 120 may be configured to cover the cylindrical portion of insulating rod 2 above mounting bracket 4, and lower shed sleeve 130 may be configured to cover the cylindrical portion of insulating rod 2 below mounting bracket 4. [0020] Fig. 5A is side perspective view of upper shed sleeve 120. Fig. 5B is a side perspective view of an upper shed sleeve 520 according to another implementation described herein. Referring collectively to Figs. 3 and 5A, a stem section 126 of upper shed sleeve 120 may be shaped so that upper shed sleeve 120 may slide completely over the top portion of insulating rod 2 and that central bore 124 may terminate against top end bracket 1 when support bracket 0 is assembled. Lower shed sleeve 130 (not shown in Fig. 5A) may be similarly configured and assembled onto the lower portion of insulating rod 2. [0021] In contrast, referring collectively to Figs. 3 and 5B, upper shed sleeve 520 may include a stem section 526 that incorporates an integrated gasket 522 with a hex-shaped opening 524. Hex-shaped opening 524 may be sized to fit/stretch over the hex portion of threaded standoff 8. Gasket 522 may join to stem section 526 to partially cover central bore 124 and prevent insertion of upper shed sleeve 520 past shoulder 9 of insulating rod 2. Thus, when support bracket 0 is assembled using upper shed sleeve 520 instead of upper shed sleeve 120, top end bracket 1 may be secured over the hex portion of threaded standoff 8 and gasket to form a seal between shoulder 9 of insulating rod 2 and top end bracket 1. Also, gasket 112 may seal between top end bracket 1 and nut 114 to provide a weatherproof seal around the top end of insulating core 3. A lower shed sleeve (not shown) may be configured similarly to upper shed sleeve 520 and assembled onto the lower portion of insulating rod 2. [0022] Fig. 6 is an exploded side view showing mounting bracket 4 with a side cross-section view of an upper shed sleeve 620 according to another implementation described herein. Upper shed sleeve 620 may generally be configured similarly to upper shed sleeve 120 with central bore 124. However, as shown in Fig. 6, an extension 621 may be included at the bottom of upper shed sleeve 620. Extension 621 may include a larger diameter bore 622 than that of central bore 124. Bore 622 may allow upper shed sleeve 620 to overlap or receive a portion of ring 6 of mounting bracket 4 when both shed sleeve 620 and mounting bracket 4 are installed over insulating rod 2. Extension 621 may, thus, cover the interface between the top edge of ring 6 and a shoulder 623 at the junction of central bore 124 and extension bore 622. Depending on the axial length of extension 621, in one implementation, extension 621 may include a notch 624 to avoid blockage by elbow section 5 of mounting bracket 4. [0023] Fig. 7 is a side view of a support bracket 700, according to another implementation described herein. As shown in Fig. 7, a single shed sleeve 720 may be used to cover insulating rod 2. Similar to upper shed sleeve 120 and lower shed sleeve 130, shed sleeve 720 may include fins 722 and a central bore with a circumference sized such that it may be stretched over the circumference of insulating rod 2 to provide an interference fit. In the configuration of Fig. 7, shed sleeve 720 may be installed over insulating rod 2 prior to a mounting bracket 704 being attached. Mounting bracket 704 may be attached, for example, over a portion of both insulating rod 2 and shed sleeve 720. Thus, in contrast with mounting bracket 4 (e.g., Fig. 3), mounting bracket 704 may use a clamp fitting 706 and/or a two-piece fitting to enable mounting bracket 704 to be positioned over insulating rod 2 and shed sleeve 720. In another implementation, a different configuration for the mounting bracket may be used to secure mounting bracket at either end of insulating rod 2. [0024] Fig. 8 is a flow diagram of an exemplary process for assembling a support bracket for a fuse cutout according to an implementation described herein. As shown in Fig. 8, process 800 may include providing am insulating cylindrical rod (block 8) and securing the mounting bracket to a middle portion of the rod (block 820). For example, insulating rod 2 including threaded standoffs 8 may be provided. Mounting bracket 4 may be slid over insulating rod 2 and secured with pin 7. [0025] Process 800 may also include sliding a premolded upper shed sleeve over an outside surface of a top portion of the insulating rod to form dielectric interface 4

5 7 EP A1 8 between the outside surface of the top portion and the interior surface of the upper shed sleeve (block 830). For example, upper shed sleeve 120 may be pushed over a top end of insulating rod 2 so that the top portion of insulating rod 2 fills central bore 124 and forms a dielectric interface between insulating rod 2 and upper shed sleeve 120 along the exterior of insulating rod 2 between mounting bracket 4 and top threaded standoff 8. [0026] Process 800 may also include sliding a premolded lower shed sleeve over an outside surface of a bottom portion of the insulating rod to form dielectric interface between the outside surface of the bottom portion and the interior surface of the lower shed sleeve (block 840). For example, lower shed sleeve 130 may be pushed over a bottom end of insulating rod 2 so that the bottom portion of insulating rod 2 fills central bore 132 and forms a dielectric interface between insulating rod 2 and lower shed sleeve 130 along the exterior of insulating rod 2 between mounting bracket 4 and bottom threaded standoff 8. [0027] Providing pre-molded shed sleeves that may be applied over an insulating rod for a fuse cutout support bracket, simplifies manufacturing and eliminates the complicated overmolding process used to manufacture conventional support brackets. Additionally, the premolded shed sleeves reduce instances of manually removing flash. Flash from the conventional molding process must be removed (typically manually) after the part is molded to avoid tracking on the flash line due to contamination buildup. Similarly, scrap from molding defects during manufacturing can be reduced by eliminating instances where an entire support bracket must be scrapped due to defects in a shed. Furthermore, material types for sheds may be easily adapted to meet customer preferences (e.g., a preference for silicone or EPDM). Also, implementations using pre-molded shed sleeves that leave the mounting bracket (e.g., mounting bracket 4) uncovered may eliminate known problems with erosion through the shed insulation around the mounting bracket. [0028] The foregoing description of exemplary implementations provides illustration and description, but is not intended to be exhaustive or to limit the embodiments described herein to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practice of the embodiments. [0029] Although the invention has been described in detail above, it is expressly understood that it will be apparent to persons skilled in the relevant art that the invention may be modified without departing from the spirit of the invention. Various changes of form, design, or arrangement may be made to the invention without departing from the spirit and scope of the invention. Therefore, the above-mentioned description is to be considered exemplary, rather than limiting, and the true scope of the invention is that defined in the following claims [0030] No element, act, or instruction used in the description of the present application should be construed as critical or essential to the invention unless explicitly described as such. Also, as used herein, the article "a" is intended to include one or more items. Further, the phrase "based on" is intended to mean "based, at least in part, on" unless explicitly stated otherwise. Claims 1. A support bracket for a fuse cutout, comprising: an insulating rod having a top portion, a bottom portion opposite the top portion, and a middle portion between the top portion and the bottom portion; a first shed sleeve secured, via an interference fit, over an outside surface of the top portion, wherein an interior surface of the first shed sleeve forms a dielectric interface between the outside surface of the top portion and the interior surface of the first shed sleeve; a second shed sleeve secured, via another interference fit over, an outside surface of the bottom portion, wherein an interior surface of the second shed sleeve forms a dielectric interface between the outside surface of the bottom portion and the interior surface of the second shed sleeve; and a mounting bracket secured to the middle portion of the insulating rod between the first shed sleeve and the second shed sleeve. 2. The support bracket of claim 1, wherein the first shed sleeve includes a plurality of fins extending radially from an exterior surface of the first shed sleeve, and wherein the second shed sleeve includes a plurality of fins extending radially from an exterior surface of the second shed sleeve. 3. The support bracket of claims 1 or 2, wherein the insulating rod comprises fiberglass material. 4. The support bracket of any one of claims 1-3, wherein the first shed sleeve and the second shed sleeve each comprises an ethylene-propylene-dienemonomer (EPDM) elastomer, silicone, or a thermoplastic elastomer. 5. The support bracket of any one of claims 1-4, wherein the first shed sleeve includes a different configuration than the second shed sleeve. 6. The support bracket of any one of claims 1-5, wherein the mounting bracket includes a ring, adjacent to the middle portion of the insulating rod, and a flange extending from the ring, and 5

6 9 EP A1 wherein at least a portion of the ring remains uncovered by the first shed sleeve and the second shed sleeve. 7. The support bracket of any one of claims 1-5, wherein the mounting bracket includes a ring, adjacent to the middle portion of the insulating rod, and a flange extending from the ring, and wherein the first shed sleeve or the second shed sleeve overlaps at least a portion of the ring. 8. The support bracket of any one of claims 1-7, further comprising: a threaded standoff at an end of the top portion, and an end bracket mounted over the threaded standoff, wherein the first shed sleeve includes an integrated gasket to seal around the threaded standoff between the end bracket and the insulating rod. 9. A method for assembling a fuse cutout, the method comprising: providing an insulating rod having a top portion, a bottom portion opposite the top portion, and a middle portion between the top portion and the bottom portion; securing a mounting bracket to the middle portion of the insulating rod; sliding a first pre-molded shed sleeve over an outside surface of the top portion, wherein an interior surface of the first pre-molded shed sleeve forms a dielectric interface between the outside surface of the top portion and the interior surface of the first pre-molded shed sleeve; and sliding a second pre-molded shed sleeve over an outside surface of the bottom portion, wherein an interior surface of the second pre-molded shed sleeve forms a dielectric interface between the outside surface of the bottom portion and the interior surface of the second pre-molded shed sleeve sleeve; and removing, prior to sliding the second pre-molded shed sleeve, flash from the second pre-molded shed sleeve. 12. The method of any one of claims 9-11, further comprising: securing, to an end of the top portion, a first end bracket, and securing, to an end of the bottom portion, a second end bracket. 13. A support bracket for a fuse cutout, comprising: an insulating rod including a first threaded standoff at a top end of the insulating rod and a second threaded standoff at a bottom end of the insulating rod; a pre-molded shed sleeve secured over an outside surface of the insulating rod between the first threaded standoff and the second threaded standoff, wherein an interior surface of the shed sleeve forms a dielectric interface between the outside surface of the insulating rod and the interior surface of the shed sleeve; and a mounting bracket secured to a portion of the support bracket between the first threaded standoff and the second threaded standoff. 14. The support bracket of claim 13, wherein the mounting bracket is secured over the insulating rod and the shed sleeve. 15. The support bracket of claim 13, wherein the mounting bracket is secured to the portion of the insulating rod and over a portion of the shed sleeve.. The method of claim 9, wherein the first pre-molded shed sleeve engages the outside surface of the top portion via an interference fit, and wherein the second pre-molded shed sleeve engages the outside surface of the bottom portion via an interference fit The method of claims 9 or, further comprising: 55 removing, prior to sliding the first pre-molded shed sleeve, flash from the first pre-molded shed 6

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17 REFERENCES CITED IN THE DESCRIPTION This list of references cited by the applicant is for the reader s convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard. Patent documents cited in the description US A [0001] 17